| /* |
| * Copyright (c) 1997, 2017, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. Oracle designates this |
| * particular file as subject to the "Classpath" exception as provided |
| * by Oracle in the LICENSE file that accompanied this code. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| */ |
| |
| package com.sun.crypto.provider; |
| |
| import java.security.InvalidKeyException; |
| import java.security.ProviderException; |
| |
| /** |
| * This class represents ciphers in output-feedback (OFB) mode. |
| * |
| * <p>This mode is implemented independently of a particular cipher. |
| * Ciphers to which this mode should apply (e.g., DES) must be |
| * <i>plugged-in</i> using the constructor. |
| * |
| * <p>NOTE: This class does not deal with buffering or padding. |
| * |
| * @author Gigi Ankeny |
| */ |
| final class OutputFeedback extends FeedbackCipher { |
| |
| /* |
| * output buffer |
| */ |
| private byte[] k = null; |
| |
| /* |
| * register buffer |
| */ |
| private byte[] register = null; |
| |
| /* |
| * number of bytes for each stream unit, defaults to the blocksize |
| * of the embedded cipher |
| */ |
| private int numBytes; |
| |
| // variables for save/restore calls |
| private byte[] registerSave = null; |
| |
| OutputFeedback(SymmetricCipher embeddedCipher, int numBytes) { |
| super(embeddedCipher); |
| if (numBytes > blockSize) { |
| numBytes = blockSize; |
| } |
| this.numBytes = numBytes; |
| k = new byte[blockSize]; |
| register = new byte[blockSize]; |
| } |
| |
| /** |
| * Gets the name of this feedback mode. |
| * |
| * @return the string <code>OFB</code> |
| */ |
| String getFeedback() { |
| return "OFB"; |
| } |
| |
| /** |
| * Initializes the cipher in the specified mode with the given key |
| * and iv. |
| * |
| * @param decrypting flag indicating encryption or decryption |
| * @param algorithm the algorithm name |
| * @param key the key |
| * @param iv the iv |
| * |
| * @exception InvalidKeyException if the given key is inappropriate for |
| * initializing this cipher |
| */ |
| void init(boolean decrypting, String algorithm, byte[] key, byte[] iv) |
| throws InvalidKeyException { |
| if ((key == null) || (iv == null) || (iv.length != blockSize)) { |
| throw new InvalidKeyException("Internal error"); |
| } |
| this.iv = iv; |
| reset(); |
| // always encrypt mode for embedded cipher |
| embeddedCipher.init(false, algorithm, key); |
| } |
| |
| /** |
| * Resets the iv to its original value. |
| * This is used when doFinal is called in the Cipher class, so that the |
| * cipher can be reused (with its original iv). |
| */ |
| void reset() { |
| System.arraycopy(iv, 0, register, 0, blockSize); |
| } |
| |
| /** |
| * Save the current content of this cipher. |
| */ |
| void save() { |
| if (registerSave == null) { |
| registerSave = new byte[blockSize]; |
| } |
| System.arraycopy(register, 0, registerSave, 0, blockSize); |
| } |
| |
| /** |
| * Restores the content of this cipher to the previous saved one. |
| */ |
| void restore() { |
| System.arraycopy(registerSave, 0, register, 0, blockSize); |
| } |
| |
| /** |
| * Performs encryption operation. |
| * |
| * <p>The input plain text <code>plain</code>, starting at |
| * <code>plainOffset</code> and ending at |
| * <code>(plainOffset + plainLen - 1)</code>, is encrypted. |
| * The result is stored in <code>cipher</code>, starting at |
| * <code>cipherOffset</code>. |
| * |
| * @param plain the buffer with the input data to be encrypted |
| * @param plainOffset the offset in <code>plain</code> |
| * @param plainLen the length of the input data |
| * @param cipher the buffer for the result |
| * @param cipherOffset the offset in <code>cipher</code> |
| * @exception ProviderException if <code>plainLen</code> is not |
| * a multiple of the <code>numBytes</code> |
| * @return the length of the encrypted data |
| */ |
| int encrypt(byte[] plain, int plainOffset, int plainLen, |
| byte[] cipher, int cipherOffset) { |
| |
| if ((plainLen % numBytes) != 0) { |
| throw new ProviderException("Internal error in input buffering"); |
| } |
| int nShift = blockSize - numBytes; |
| int loopCount = plainLen / numBytes; |
| |
| for (; loopCount > 0; |
| plainOffset += numBytes, cipherOffset += numBytes, |
| loopCount--) { |
| embeddedCipher.encryptBlock(register, 0, k, 0); |
| for (int i = 0; i < numBytes; i++) { |
| cipher[i + cipherOffset] = |
| (byte)(k[i] ^ plain[i + plainOffset]); |
| } |
| if (nShift != 0) { |
| System.arraycopy(register, numBytes, register, 0, nShift); |
| } |
| System.arraycopy(k, 0, register, nShift, numBytes); |
| } |
| return plainLen; |
| } |
| |
| /** |
| * Performs last encryption operation. |
| * |
| * <p>The input plain text <code>plain</code>, starting at |
| * <code>plainOffset</code> and ending at |
| * <code>(plainOffset + plainLen - 1)</code>, is encrypted. |
| * The result is stored in <code>cipher</code>, starting at |
| * <code>cipherOffset</code>. |
| * |
| * @param plain the buffer with the input data to be encrypted |
| * @param plainOffset the offset in <code>plain</code> |
| * @param plainLen the length of the input data |
| * @param cipher the buffer for the result |
| * @param cipherOffset the offset in <code>cipher</code> |
| * @return the length of the encrypted data |
| */ |
| int encryptFinal(byte[] plain, int plainOffset, int plainLen, |
| byte[] cipher, int cipherOffset) { |
| int oddBytes = plainLen % numBytes; |
| int len = encrypt(plain, plainOffset, (plainLen - oddBytes), |
| cipher, cipherOffset); |
| plainOffset += len; |
| cipherOffset += len; |
| |
| if (oddBytes != 0) { |
| embeddedCipher.encryptBlock(register, 0, k, 0); |
| for (int i = 0; i < oddBytes; i++) { |
| cipher[i + cipherOffset] = |
| (byte)(k[i] ^ plain[ i + plainOffset]); |
| } |
| } |
| return plainLen; |
| } |
| |
| // OFB encrypt and decrypt are identical |
| int decrypt(byte[] cipher, int cipherOffset, int cipherLen, |
| byte[] plain, int plainOffset) { |
| return encrypt(cipher, cipherOffset, cipherLen, plain, plainOffset); |
| } |
| |
| // OFB encrypt and decrypt are identical |
| int decryptFinal(byte[] cipher, int cipherOffset, int cipherLen, |
| byte[] plain, int plainOffset) { |
| // OFB encrypt and decrypt are identical |
| return encryptFinal(cipher, cipherOffset, cipherLen, plain, plainOffset); |
| } |
| } |